Powered surgical stapling device

ABSTRACT

A medical instrument having a tool assembly attachable to a distal end of the medical instrument is disclosed. The tool assembly includes a pair of opposing tissue engaging surfaces for clamping tissue therebetween. The medical instrument also includes a housing having a fixed handle and a movable handle mounted to the housing and selectively movable relative to the fixed handle from a first position in spaced relation relative to the fixed handle to a second position closer to the fixed handle to actuate the clamping of tissue. The instrument further includes a selectively activatable drive assembly including a power source and a motor which is operatively coupled to the movable handle, wherein upon actuation the motor actuates the pair of opposing tissue engaging surfaces. The drive assembly also includes a controller configured to variably control the rate at which the motor actuates the pair of opposing tissue engaging surfaces in response to the force exerted on the movable handle.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.12/177,954 filed Jul. 23, 2008, now U.S. Pat. No. 7,637,409, which is acontinuation of U.S. patent application Ser. No. 11/724,744 filed onMar. 15, 2007, now U.S. Pat. No. 7,422,136, by Stanislaw Marczyk. Thedisclosures of which are hereby incorporated by reference in itsentirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a surgical stapler for implantingmechanical surgical fasteners into the tissue of a patient, and, inparticular, to a surgical stapler which is powered by a motor for firingsurgical fasteners into tissue.

2. Background of Related Art

Current known devices can typically require 10-60 pounds of manual handforce to clamp tissue and deploy and form surgical fasteners in tissuewhich, over repeated use, can cause a surgeon's hand to become fatigued.

Gas powered pneumatic staplers which implant surgical fasteners intotissue are known in the art. Certain of these instruments utilize apressurized gas supply which connects to a trigger mechanism by way ofan intricate series of hoses and actuators. The trigger mechanism, whendepressed, simply releases pressurized gas to implant a fastener intotissue.

Motor-powered surgical staplers are also known and are disclosed in U.S.Pat. No. 5,383,880 to Hooven and U.S. Pat. No. 6,716,233 to Whitman. The'880 and the '233 patents disclose powered surgical staplers includingmotors which activate staple firing mechanisms. In particular, the '880patent discloses a powered stapler wherein the power of the motor isautomatically controlled based on various types of sensor data (e.g.,tissue thickness). The '233 patent teaches a powered stapler that isautomatically controlled as a function of sensor data. However, both ofthese references only provide for limited user control of the staplingprocess. The '880 and '233 patents provide the user with the option oftoggling a single switch and/or button to actuate the powered staplerwhich then automatically controls the motor and applies correspondingtorque to the stapler's firing mechanisms. Consequently, in thesereferences, the user only controls activation and deactivation of thedevice and the device does not provide any tactile feedback.

It would be desirable to provide a low cost motor powered stapler thatprovides the needed energy required to fire the instrument to form aseries of surgical fasteners into and through tissue. It would also bedesirable to provide an ergonomically advanced surgical stapler whichreduces fatigue during repeated use and provides the surgeon with moretactile feedback during activation of the stapler. It would further bedesirable to provide a powered stapler which provides the user withtactile feedback allowing to user to vary the force applied by the motoron the stapling and/or clamping mechanisms.

SUMMARY

According to one aspect of the present disclosure, a medical instrumenthaving a tool assembly attachable to a distal end of the medicalinstrument is disclosed. The tool assembly includes a pair of opposingtissue engaging surfaces for clamping tissue therebetween. The medicalinstrument also includes a housing having a fixed handle and a movablehandle mounted to the housing and selectively movable relative to thefixed handle from a first position in spaced relation relative to thefixed handle to a second position closer to the fixed handle to actuatethe clamping of tissue. The instrument further includes a selectivelyactivatable drive assembly including a power source and a motor which isoperatively coupled to the movable handle, wherein upon actuation themotor actuates the pair of opposing tissue engaging surfaces. The driveassembly also includes a controller configured to variably control therate at which the motor actuates the pair of opposing tissue engagingsurfaces in response to the force exerted on the movable handle.

According to another aspect of the present disclosure A medicalinstrument is disclosed. The medical instrument includes a tool assemblyattachable to a distal end of the medical instrument, the tool assemblyincluding a pair of opposing tissue engaging surfaces. The instrumentalso includes a selectively activatable drive assembly including a motorwhich is operatively coupled to a movable handle, wherein upon actuationthe motor actuates the pair of opposing tissue engaging surfaces. Theselectively activatable drive assembly also includes a controllerconfigured to variably control the rate at which the motor actuates thepair of opposing tissue engaging surfaces in response to the forceexerted on the movable handle.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the subject instrument are described herein withreference to the drawings wherein:

FIG. 1 is a schematic, side view with portions broken away of a surgicalstapler according to the present disclosure having a motor-powered driveassembly for forming fasteners;

FIG. 2 is a schematic, side view with portions broken away of analternate embodiment of a tool assembly for use with the stapler of FIG.1; and

FIG. 3 is a schematic, side view with portions broken away of a surgicalstapler according to an embodiment of the present disclosure; and

FIG. 4 is a schematic, side view with portions broken away of a surgicalstapler according to another embodiment of the present disclosure.

DETAILED DESCRIPTION

Referring initially to the embodiment disclosed in FIGS. 1 and 2, asurgical stapler 10 is shown having a motor-powered drive assembly hereshown as including a drive assembly 20. It is envisioned that thepresently disclosed drive assembly 20 can be utilized with any type ofknown surgical stapler. As such, a general surgical stapler 10 isschematically depicted in the drawings and described herein. Forexample, stapler 10 includes a housing 12 having an elongated member orshaft 30 attached thereto. Shaft 30 includes a proximal end 32 whichattaches to a distal end 21 of the housing 12 and a distal end 34 whichoperatively couples to a tool assembly such as an end effector 100 or atool assembly 200. The end effector 100 depicted in FIG. 1 is aconventional longitudinal stapler having opposing tissue contactingsurfaces 110 and 120. The contact surface 110 acts as an anvil assembly113 and the contact surface 120 includes a cartridge assembly 111 havinga plurality of surgical fasteners 115. During operation, as the contactsurfaces 110 and 120 are closed about tissue, the surgical fasteners 115are fired from the cartridge assembly 111, through tissue, and thesurgical fasteners are deformed by the anvil assembly of the contactsurface 110 as discussed in more detail below.

The tool assembly 200 depicted in FIG. 2 is that of a conventionalcircular stapler (not shown) having opposing tissue contacting surfaces210 and 220, wherein the contacting surface 210 is formed on the anvilassembly and the contact surface 220 is formed on the cartridgeassembly. For the purposes herein, stapler 10 will be described ashaving tool assembly 100 attached to distal end 34 of an elongate shaft.

Housing 12 includes a fixed handle 65 which is generally in the form ofa pistol grip to enhance manipulation of the stapler 10 as needed duringsurgery. Stapler 10 also includes a movable handle 60 which is movablerelative to fixed handle 65 (in the direction “A”) to actuate opposingtissue contacting surfaces 110 and 120 of tool assembly 100 tomanipulate, grasp fasten and cut tissue. The proximal end of shaft 30 isintegrally associated with, mounted to, or selectively attachable tohousing 12. One or more actuating assemblies are incorporated withinhousing 12 and may include manual, robotic or computer operated systems.The actuating assembly may comprise that of a known open or endoscopicsurgical stapler. Many types of mechanical actuators and handlemechanisms are known which are configurable to communicate with andactuate the functions of tool assembly 100. Mechanical actuators andhandle mechanisms are disclosed in U.S. Pat. Nos. 5,318,221, 5,762,256and 5,865,361, the disclosures of which are hereby incorporated byreference herein.

As best seen in FIG. 1, a staple deformation or staple firing mechanism70 (e.g., firing piston) and knife assembly 75 may also be included indistal end 34 of the shaft 30 and/or included with tool assembly 100. Itis contemplated that the same or separate actuating mechanisms may beemployed to drive staple firing mechanism 70 and knife assembly 75. Themovable handle 60 cooperates with tool assembly 100 to grasp tissue, asis known in the art. The movable handle 60 also actuates the driveassembly 20 which drives the staple firing mechanism 70 and/or the knifeassembly 75 through tissue. The staple firing mechanism 70 may beconfigured as a longitudinally movable member or beam that pushes anactuation sled through cartridge assembly 111 to deploy staples againstthe anvil assembly 110, as is known in the art. Such a mechanism isdisclosed in U.S. Patent Application Publication No. 2004/0232201, thedisclosure of which is hereby incorporated by reference herein, in itsentirety.

FIG. 1 shows one embodiment of a stapler 10 which includes the driveassembly 20 housed within surgical stapler 10 to actuate a firing shaft55 which, in turn, cooperates with tool assembly 100 to clamp tissuebetween tissue engaging surfaces 110 and 120 and to drive a plurality ofsurgical fasteners 115. For example, as disclosed in U.S. PatentPublication No. 2004/0232201, the drive beam may include a member, suchas a cam roller, for engaging a cam surface of the anvil assembly toapproximate the cartridge assembly and anvil assembly and to clamptissue therebetween. The same drive beam may also be used to deploy thestaples from the cartridge assembly. The disclosure of U.S. PatentApplication Publication No. 2004/0232201 is hereby incorporated byreference herein. Surgical stapler 10 is preferably, as shown, designedfor one-handed operation by the user and requires minimal pulling forceof the movable handle 60 to deform the surgical fasteners 115 throughtissue. In other words, stapler 10 is designed such that drive assembly20 actuates and controls the high-force portion of the activationsequence (i.e., the so-called “firing stroke”) thus alleviating userfatigue and allowing simple, consistent and repeated use of the staplerduring surgery.

The drive assembly 20 includes a coupling member 90 operatively coupledto a shaft connector 92 which is coupled to the firing shaft 55, suchthat longitudinal movement of the coupling member 90 in the direction“D” is translated to the firing shaft 55. The coupling member 90includes a ratchet track 94 having one or more teeth interfacing with apawl 96 allowing for unidirectional motion. The pawl 96 is rotativelycoupled to the movable handle 60 via a pin 98, such that when themovable handle 60 is pulled toward the handle 65, the pawl 98 engagesone of the teeth of the ratchet track 94 and pushes the coupling member90 in the distal direction “D.” The staple firing mechanism 70 isadvanced by the distal movement of the coupling member 90 and firingshaft 55. The staple firing mechanism 70 engages the anvil assembly 113and cartridge assembly 111 to clamp tissue therebetween. Furtheractuation of the staple firing mechanism deploys staples from the staplecartridge assembly 111 and deforms the staples against the anvilassembly 113.

The coupling member 90 includes a lumen defined therein havingsupporting walls 130 and 131. The supporting wall 130 along with theshaft connector 92 encloses a spring 32 or another compressionmechanism. The spring 32 applies pressure onto supporting wall 130 whichin turn pushes the coupling member 90 in the proximal direction “C.” Thepressure on the coupling member 90 also moves apart the movable handle60 away from the fixed handle 65, keeping the movable handle 60 in anunactuated position (e.g., first position).

The drive assembly 20 includes an electric DC motor 144 connected to apower source 142 (e.g., a battery). A variable resistor 140 and a switch80 are connected in series with the DC motor 144 and the power source142. The switch 80 is open when the movable handle 60 is in the firstposition and is closed when then movable handle 60 is pulled in theproximal direction into the second position actuating the couplingmember 90. In particular, a contact 82 disposed on the movable handle 60contacts a contact 81 disposed on the fixed handle 65. Once the contacts81 and 82 are touching, the switch 80 is closed and the DC motor 144 isactivated. It is envisioned that the switch 80 may be implemented via avariety of embodiments known to those skilled in the art, such as a pushbutton switch being disposed on the fixed handle 65 and being activatedby physical contact of the movable handle 60 as the movable handle 60 isactuated. As discussed above, the spring 132 biases the movable handle60 away from the fixed handle 65 to maintain the switch 80 in an openposition thereby preventing inadvertent activation of the DC motor 144.More specifically, the spring 132 biases the coupling member 90 byacting on a housing portion 12 a and supporting wall 130.

The DC motor 144 is coupled to a unidirectional clutch 146 whichinterfaces with a pinion gear 148. Once the DC motor 144 is activated bypulling of the movable handle 60, the clutch 146 rotates in a clockwisedirection rotating the gear 148 in the clockwise direction as well. Thegear 148 interfaces with a rack surface 95 of the coupling member 90 andthe rotational motion of the gear 148 translates the coupling member 90in a longitudinal motion, advancing the coupling member 90 and thefiring rod 55 in a distal direction “D.”

The rate at which the DC motor 144 rotates, and hence, the rate at whichthe firing shaft 55 is moved in the distal direction, is controlled viathe variable resistor 140. In FIG. 1 the variable resistor 140 is shownas a potentiometer 141 with a contact 143 (e.g., wiper terminal)disposed in contact therewith. The contact 143 is coupled to the shaftconnector 92 via a shaft 134. The contact 143 slides along the surfaceof the potentiometer 141 as the coupling member 90 is moved in thedistal direction by pulling of the movable handle 60. As the contact 143slides across the potentiometer 141 the voltage supplied to the DC motor144 varies accordingly. In particular, varying the position of thecontact 143 along the potentiometer 141 adjusts the rate of rotation ofthe DC motor 144. The distance the contact 143 moves along thepotentiometer 141 is proportional to the force exerted by the user inpulling the movable handle 60. As the movable handle 60 is moved,contact 143 moves a distance, and the pulling force on the movablehandle 60 is counterbalanced by the force of the spring 132 on themovable handle 60. The further the contact 142 moves under the pullingaction on the movable handle 60, the more compression force is appliedby the spring 132. Consequently, the rate of rotation of the DC motor144 and the force with which the firing shaft 55 is moved distally isproportional to the pulling force. Namely, when resistance inpotentiometer 141 is low, the torque form the DC motor 144 is high andwhen the resistance in potentiometer 141 is high, the torque from the DMmotor 144 is low.

The switch 80 is arranged to allow clamping of tissue before the motor144 is actuated. This provides for user control of the initial graspingof the tissue with the end effector 100 and subsequent power-assistedfiring of surgical fasteners 115. Those skilled in the art willappreciate that the disclosed variable resistor 140 may also be arheostat.

Use of the surgical stapler 10 is as follows. The surgical stapler ispositioned with the end effector 100 at the surgical site and the tissueengaging surfaces 110 and 120 are placed around tissue. The userthereafter initiates the stapling process by pulling on the movablehandle 60 to bring the movable handle 60 toward the fixed handle 65 andclamp tissue. With further movement of movable handle 60, the switch 80is closed. Simultaneously, the movable handle 60 moves the couplingmember 90 in the distal direction along the direction “C” thereby movingthe contact 143 along the potentiometer 141. The clamping force exertedby the pulling of the movable handle 60 is counterbalanced by the tissuebeing grasped and the spring 132. As the movable handle 60 moves thecoupling member 90, the contact 143 moves along the potentiometer 141,adjusting the voltage supplied to the DC motor 144. The DC motor 144rotates at the rate corresponding to the supplied voltage as varied bythe variable resistor 140. In response thereto, the DC motor 144actuates the pinion gear 148 via the unidirectional clutch 146. Therotational motion of the pinion gear 148, which interfaces with the racksurface 95, is translated into longitudinal motion of the couplingmember 90 and the firing shaft 55. The firing shaft 55 forces the staplefiring mechanism 70 and knife assembly 75 through tissue to sequentiallyfasten and separate the tissue. Consequently, the rates at which theopposing tissue contacting surfaces 110 and 120 are closed and thestaples are fired are directly proportional to the pulling force on themovable handle 60. This provides the user with tactile feedback duringthe stapling process. Those skilled in the art will appreciate that aseries of gears, shafts, screws or other mechanisms may be employed toconvert the rotational energy of the drive assembly 20 to firing shaft55 to actuate tool assembly 100. The drive assembly 20 desirablyincludes a switch for reversing the motor 144 for retracting the staplefiring mechanism 70, and releasing the end effector 100 from tissue. Abutton may be provided on the housing 12 to actuate the switch.

FIG. 3 shows another embodiment of the surgical stapler 10 whichutilizes the potentiometer 141 as a switch to activate the driveassembly 20. In this embodiment, switch 80 and hence contacts 81, 82 arenot used. When the movable handle 60 is in the open position away fromthe fixed handle 65, the potentiometer 141 does not electrically contactthe contact 143. When the movable handle 60 is brought toward the fixedhandle 65 to clamp tissue, the potentiometer 141 is brought into contactwith the contact 143 and the drive assembly 20 is activated. The driveassembly 20 is controlled by varying the voltage as the potentiometer141 is sliding across the contact 143, which corresponds to the clampforce being applied to the movable handle 60.

FIG. 4 shows a further embodiment of the surgical stapler 10 having aswitch assembly 200. The switch assembly 200 is used in place of thepotentiometer 141, contact 143 and the switch 80. The switch assembly200 includes a handle 201 which is pivotally coupled to the fixed handle65. The handle 201 is biased by a spring 203 against the fixed handle65. The switch assembly 200 also includes a pressure sensor 202 disposedbetween the fixed handle 65 and the handle 201. The pressure sensor 201may be a piezoelectric sensor configured to sense pressure applied bythe handle 201. During clamping, as the movable handle 60 is pulledtoward the fixed handle 65, the handle 201 is pushed toward the fixedhandle 65. The pressure sensor 202 records pressure applied on thehandle 201 as sensor signals, which are representative of the clampingforce, and transmits the signals to a motor controller 204. The motorcontroller 204 thereafter controls the drive assembly 20 based on thesensor signals. The rates at which the opposing tissue contactingsurfaces 110 and 120 are closed and the staples are fired are directlyproportional to the pushing force on the handle 201.

Preferably, the presently disclosed staplers are designed for endoscopicuse and are dimensioned to fit through a trocar or cannula for variousendoscopic and laparoscopic procedures. As can be appreciated, theoverall dimensions of the tool assembly and the elongated shaft aresized accordingly to fit through the trocar or cannula. Alternatively,the presently disclosed staplers may also be designed and/or used foropen surgical procedures. The disclosed surgical staplers preferably aresuitable for one-handed operation by the user.

The surgical stapler of FIG. 1 has a staple firing mechanism 70 thatdeploys staples from the staple cartridge assembly, as well as engagesthe cartridge assembly and anvil assembly to clamp tissue therebetween.It is contemplated that separate clamping and firing mechanisms may beused. By way of example, the anvil assembly and cartridge assembly maybe approximated using a tube that is separate from the staple firingmechanism, as disclosed in U.S. Pat. No. 5,318,221, the disclosure ofwhich is hereby incorporated by reference herein.

It will be understood that various modifications may be made to theembodiments shown herein. Therefore, the above description should not beconstrued as limiting, but merely as exemplifications of preferredembodiments. Those skilled in the art will envision other modificationswithin the scope and spirit of the claims appended hereto.

1. A medical instrument, comprising: a housing having a fixed handle; anelongated shaft extending distally from the housing; a tool assemblycoupled to a distal end of the elongated shaft, the tool assemblyincluding a pair of opposing tissue engaging surfaces for clampingtissue therebetween; a movable handle mounted to the housing andselectively movable relative to the fixed handle from a first positionin spaced relation relative to the fixed handle to a second positioncloser to the fixed handle; a firing shaft extending at least partiallythrough the elongated shaft, wherein the firing shaft is operativelycoupled to the movable handle such that movement of the movable handletoward the second position advances the firing shaft through theelongated shaft, and wherein the firing shaft is operatively coupled tothe tool assembly to induce motion in the tool assembly; a driveassembly including a motor and a controller, wherein the motor isoperatively engaged with the firing shaft to supply a longitudinal forcethereto, and wherein the controller is configured to variably control avoltage supplied to the motor in response to longitudinal motion of thefiring shaft.
 2. A medical instrument according to claim 1, wherein thecontroller includes a variable resistor to regulate the voltage suppliedto the motor.
 3. A medical instrument according to claim 2, wherein thevariable resistor includes a potentiometer and a contact, and whereinthe contact is coupled to the firing shaft such that longitudinal motionof the firing shaft is transmitted to the contact to move the contactalong the potentiometer, and wherein the voltage supplied to the motoris varied depending on the position of the contact with respect to thepotentiometer.
 4. A medical instrument according to claim 3, wherein thecontact is decoupled from the potentiometer when the movable handle isin the first position, and wherein movement of the movable handle towardthe second position moves the contact into contact with thepotentiometer to actuate the motor.
 5. A medical instrument according toclaim 4, wherein one of the opposing tissue engaging surfaces is ananvil assembly and another of the opposing tissue engaging surfaces is acartridge assembly including a plurality of surgical fasteners, the pairof opposing tissue engaging surfaces being adapted for deforming aplurality of surgical fasteners to fasten tissue.
 6. A medicalinstrument according to claim 5, wherein the firing shaft is movable toinitially clamp tissue when the contact is decoupled from thepotentiometer and subsequently movable to eject the surgical fastenersfrom the cartridge assembly when the contact is in contact with thepotentiometer.
 7. A medical instrument according to claim 2, wherein thevariable resistor includes a rheostat to regulate the voltage suppliedto the motor.
 8. A medical instrument according to claim 1, wherein themovable handle mechanically cooperates with the firing shaft to advancethe firing shaft through the elongated shaft.
 9. A medical instrument,comprising a tool assembly having a pair of opposing tissue engagingsurfaces for clamping tissue therebetween and for deforming a pluralityof surgical fasteners through the tissue; a firing shaft operativelyassociated with the tool assembly such that distal longitudinaladvancement of the firing shaft from a first shaft position to a secondshaft position approximates the tissue engaging surface to clamp thetissue and further distal advancement of the firing shaft from thesecond shaft position to a third shaft position deforms the plurality ofsurgical fasteners through the tissue; a drive assembly including amotor, wherein the motor is operatively engaged with the firing shaft tosupply a distally directed longitudinal force thereto when actuated; anda handle assembly including a fixed handle and a movable handle movablebetween first, second and third handle positions wherein the firsthandle position is spaced from the fixed handle, the second handleposition is closer to the fixed handle than the first handle positionand the third handle position closer to the fixed handle than the secondhandle position, and wherein the handle assembly is operativelyassociated with the drive assembly and the firing shaft such that (i)movement of the movable handle from the first handle position to thesecond handle position moves the firing shaft from the first shaftposition to the second shaft position; (ii) maintaining the movablehandle at the second handle position or between the second and thirdhandle positions actuates the motor to impart the first longitudinallydirected force to move the firing shaft from the second shaft positionto the third shaft position; and (iii) movement of the movable handlefrom the second handle position to the third handle position imparts asecond distally directed longitudinal force to the firing shaftindependent of the first distally directed longitudinal force impartedby the motor.
 10. A medical instrument according to claim 9, wherein thedrive assembly includes a controller to variably control a voltagesupplied to the motor when the motor is actuated.
 11. A medicalinstrument according to claim 10, wherein the controller is configuredto receive signals from a sensor indicative of a force applied to themovable handle and variable control the voltage supplied to the motor asa function of the force applied to the movable handle.
 12. A medicalinstrument according to claim 10, wherein the controller is configuredto variably control the voltage supplied to the motor as a function of alongitudinal position of the firing shaft.
 13. A medical instrumentaccording to claim 9, wherein the drive assembly includes a switch,wherein the switch is in an open configuration when the movable handleis between the first and second handle positions and wherein the switchis in a closed configuration when the movable handle is between thesecond and third handle positions to actuate the motor.
 14. A medicalinstrument according to claim 13, wherein the switch includes a firstcontact disposed on the movable handle and a second contact disposed onthe fixed handle.
 15. A medical instrument according to claim 9, whereinthe drive assembly includes a switch, wherein the switch is in an openconfiguration when the firing shaft is between the first and secondshaft positions and wherein the switch is in a closed configuration whenthe firing shaft is between the second and third shaft positions toactuate the motor.
 16. A medical instrument according to claim 15,wherein the switch includes a stationary contact and movable contactcoupled to the firing shaft to move longitudinally with the firing shaftwith respect to the stationary contact.
 17. A medical instrumentaccording to claim 16, wherein the stationary contact includes avariable resistor and the movable contact includes a wiper terminalconfigured for sliding contact with the variable resistor.
 18. A medicalinstrument according to claim 17, wherein the variable resistor isselected from the group consisting of a potentiometer and a rheostat.